-LRB- CNN -RRB- -- It all started with some boxes that had not been opened for 80 years .

`` There was a rumor that there were archives in the Condé Nast offices in New York that nobody had known about , '' says Todd Brandow , a photography curator .

`` It was difficult to get access , but when I finally got in , they told me that it had all been sold and nothing was left .

`` But then the archivist rolled out these boxes of 2,000 prints . It was one of those great ` oh my God ' moments . ''

Among the prints were photographic portraits of Winston Churchill , Katharine Hepburn , HG Wells , George Gershwin , Marlene Dietrich , Greta Garbo , WB Yeats , Fred Astaire , and countless other luminaries of the 1920s and 1930s .

None of the pictures had seen the light of day for eight decades , and all had been taken by the pre-eminent photographer Edward Steichen -LRB- 1879-1973 -RRB- for Vanity Fair and Vogue .

Also included in the stash were Art Deco-style portraits of women modeling designs by Chanel , Lanvin , Lelong , Schiaparelli and many others .

The photographs are now being exhibited at London 's Photographer 's Gallery , where they will show until 18 January .

The Picasso of photography

`` It was a kid-in-a-candy-store feeling , '' Brandow recalls . `` They were taken almost 100 years ago but the pictures felt so contemporary , that 's what really excited me . All the poses were so natural , and the vision was so fresh .

`` Many of them were fashion pictures , but the women looked like they 'd been born wearing those clothes , that they wore them every day . That was Steichen 's skill : he could make people look natural in every sense of the word . ''

During his lifetime , Steichen was recognized as the most important photographer of his age . Even today , says Natalie Herschdorfer , an art historian who co-curated the exhibition with Brandow , he is `` one of the top five photographers of all time '' .

`` He was the Picasso of photography , '' she says . `` He had a 70-year career covering the whole 20th Century . All the genres of modern photography are represented in his work , from the pictorial style of the 1900s to the modernist period . It 's very rare . ''

At the height of his fame , Steichen -- who borrowed from a range of aesthetic movements such as Impressionism , Art Nouveau and Symbolism to create a distinctive Art Deco style -- was being paid the equivalent of $ 1 million a year by Vanity Fair and Vogue , plus another $ 1 million by commercial clients .

But after his death he fell from prominence because his widow , Joanna , was extremely protective of the rights to his work , making exhibitions very difficult .

Now , says William A Ewing , the third of the exhibition 's co-curators , the time has come to reintroduce Steichen 's work to the world .

`` The skill of any great portrait photographer is to gain an immediacy , an intimacy , '' he says . `` You feel as if Steichen lives with his subjects . He does n't turn them into gods . He brings out their humanity .

`` He turned fashion photography into portraiture . He looked first and foremost at a woman wearing a dress , not the dress for its own sake . That 's what connected so powerfully with the viewers . ''

From steerage to First Class

The story of how Steichen came to take these iconic photographs -- and become a household name -- reads like a Hollywood rags-to-riches story .

In the early 1920s he had gone through an acrimonious divorce , and had large alimony bills that placed him in financial jeopardy . He was determined to dedicate his life to his art , and had changed his style to a modernist approach , with clean lines , strong diagonals , and high contrast .

But he did n't know how to make it pay .

In a letter to his sister , he wrote that the outlook was bleak and that he was considering abandoning photography for film , which he thought may have a more secure future .

He traveled from Paris , where he had been during the First World War , to the United States in steerage , alongside impoverished immigrants .

After he arrived , he stumbled upon an article in Vanity Fair in which , to his surprise , he was named as `` America 's greatest portrait photographer '' . He contacted the magazine and was offered a job .

Within a few weeks he was returning to France to photograph Paris Fashion Week . But this time he was on a big salary , and traveling First Class .

`` He went from rock bottom to being on top of the world almost overnight , '' says Ewing . `` You can see this reflected in his pictures , which had a sense of exuberance and confidence . ''

How Steichen worked his magic

It was Condé Montrose Nast himself who had the vision to attract Steichen 's talents to his magazines .

In their discussions , Steichen was quite open about the fact that he had no interest in haute-couture . But Nast persuaded him that `` it 's not about fashion , it 's about photography '' .

`` Those were the days before professional models , '' says Ewing . `` People used to photograph society women . But Condé Nast went to Broadway and hired actors and dancers , who knew how to get into character for the camera .

`` This enabled Steichen to work his magic . ''

It was this unique approach towards fashion photography , which was firmly rooted in the tradition of portraiture , that was one of the keys to Steichen 's success .

Steichen lived the high life for several years , photographing the world 's most famous faces . But in 1935 he burned out , and resigned to spend his time on horticultural photography , which was his great passion .

`` He really was one of the greats , '' says Brandow . `` He was the founding figure of modernism in photography and the modern woman in fashion photography , as well as modern portraiture .

`` Revealing these secret photographs will finally bring him back to the prominence he deserves . ''

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An 80-year-old stash of photographs has been unearthed in Condé Nast archives

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Unique portraits of the biggest stars of the 20s and 30s seen for the first time

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They were taken by Edward Steichen , known as `` the best photographer in the world '' at the time